1. Technical Field
The present invention relates to an optical touch system and an electronic apparatus comprising the same.
2. Related Art
FIG. 1 shows a current optical touch screen system 1 disclosed in U.S. Pat. No. 4,782,328. As shown in FIG. 1, the optical touch screen system 1 comprises two image sensors 11 configured to capture the image of an object 13 on a touch screen 12. The processor 14 is coupled with the two image sensors 11 for processing the images from the two image sensors 11 to decide sensing paths 15 respectively connecting the object 13 and the two image sensors 11, and calculates the coordinates of the object 13 using the sensing paths 15.
The coordinates of the object 13 are those of the intersection of the two sensing paths 15. The sensing path 15 is determined by sensing paths 16 that respectively pass through the corresponding edges of the object 13, and the sensing paths 16 are determined by the edges of the dark image of the object 13 captured by the image sensor 11. The detailed calculation method is disclosed in U.S. Pat. No. 4,782,328, which is incorporated herein by reference.
FIG. 2 shows another current optical touch screen system 2. U.S. Pat. No. 7,689,381 B2 (or counterpart Taiwan Publication Patent No. 201003477) discloses an optical touch screen system 2. The optical touch screen system 2 comprises a mirror 21, two light sources 22, an image sensor 23, and a processor 24. The mirror 21 and the two light sources 22 are disposed at the periphery of a touch area. The mirror 21 is configured to generate a reflection 26 of an object 25. The image sensor 23 is configured to generate an image of the object 25 and an image of the reflection 26. The processor 24 determines the coordinates of the object 25 according to the image of the object 25 and the image of the reflection 26.
The processor 24 determines a sensing path 27 passing through the image of the object 25 and another sensing path 27 passing through the image of the reflection 26. The sensing paths 27 can be determined by the calculation method disclosed in U.S. Pat. No. 4,782,328. Next, the coordinates (x, y) of the object 25 can be calculated by equations (1) and (2) as follows:
                    x        =                              2            ⁢                                                  ⁢            L                                              tan              ⁡                              (                                  θ                  1                                )                                      +                          tan              ⁡                              (                                  θ                  2                                )                                                                        (        1        )                                y        =                                            2              ⁢                                                          ⁢              L                                                      tan                ⁡                                  (                                      θ                    1                                    )                                            +                              tan                ⁡                                  (                                      θ                    2                                    )                                                              ⁢                      tan            ⁡                          (                              θ                1                            )                                                          (        2        )            
where L is the distance between the mirror 21 and the edge of a touch area opposite to the mirror 21; θ1 and θ2 are the included angles between a sensing path and an edge of the touch area.